Brazilian police have arrested 10 people they suspect of planning terrorist attacks the upcoming Olympics in Rio de Janeiro. Two more people are being sought. At a press conference today, authorities described the group is disorganized and amateur, but said that they were taking every threat seriously ahead of the games next month. NPR's Lulu Garcia-Navarro joins us from Rio de Janeiro. And, Lulu, just tell us what is known about the suspects so far and about what they were planning.

LULU GARCIA-NAVARRO, BYLINE: Yeah, Audie, as you can imagine, we're still getting information, but we know the basics. According to the minister of justice who gave that press conference, he said that they were all Brazilians. They belong to what the military police here says is a group called the Defenders of Sharia. And they communicated via instant messaging apps like WhatsApp and Telegram because they were based in different states all over the country.

It is alleged they were radicalized online and that some of them at least pledged allegiance to Islamic State, but that they had not actually coordinated with the group itself. They were also said to be planning a shooting attack of some kind, sort of like what happened in Orlando. They did not have bomb-making materials. They apparently tried to get a gun online from an illegal seller in Paraguay. And that's a particularly strange thing, considering how many illegal weapons there are in the country already.

You know, but the authorities, as you mentioned, said that the group were amateurs. They were disorganized. And that - some of the intercepted and discussions that they had, they were talking about training, learning how to do martial arts and also learning how to shoot. So clearly, this was not exactly a highly trained terror cell.

CORNISH: You touched on this a little bit, but did authorities discuss any more about a potential motive?

GARCIA-NAVARRO: So what the minister said in his press conference was that this group apparently felt that Brazil had always been neutral. It hadn't really been involved in wars in the Middle East, but that - because it was hosting a huge event like the Olympics and that "enemy countries," quote-unquote, would be sending their tourists and their athletes here, that it was a fair target. And so that was what motivated them do this, again, according to authorities.

Information is coming into us, though, and we heard from one of the wives of one of the alleged members of this terror cell. And she says that her husband converted to Islam in 2010 and that he was learning Arabic, and he was not involved in any attempt on the Olympics. So information is coming in now, and there's still a lot to uncover about exactly who these people were and what they were doing.

CORNISH: Now, Brazil has stepped up security measures since the attacks in Nice, France. What can you tell us what's being done?

GARCIA-NAVARRO: Yeah. You know, this is the biggest security operation ever at in an Olympics, Audie. Eighty-five thousand security personnel are blanketing the city. That's twice what the London summer games had. You know, as I've reported, security has been really bad in the run up to these Olympics. You've had a big crime spike. Robberies are up. Murders are up.

But now we're seeing federal troops, you know, arriving into the city. And you can see them securing key infrastructure. They've been patrolling the beach. This is starting to look like a heavily militarized city. There's a palpable difference. Security and intelligence officials have been stressing that their main concern is not terrorism, despite what happened today, but it's crime. And that's what they'll be focusing on. But certainly we do know Islamic State has called for attacks during the games.

CORNISH: That's NPR's Lulu Garcia Navarro. She joined us from Rio de Janeiro. Thanks so much, Lulu.